Module D2

Question 1

Thrombopoiesis differs from the production of other blood cells in that

Answer 1

The megakaryocytes get larger as they mature

There is no cellular division, rather there is endo mitosis within the developing megakaryocytes

The functional end product, which enters the circulation is a cytoplasmic fragment of the megakaryocyte

Question 2

Platelets or thrombocytes have a lifespan of

Answer 2

8-10 days

Question 3

Platelet morphology have 3 zones

Answer 3

Peripheral zone

Sol-gel zone

Organelle zone

Question 4

Peripheral zone (hyalomere)

Answer 4

Consists of the plasma membrane and its outer coating the glycocalyx

Question 5

Sol-gel zone

Answer 5

Lies just below the plasma membrane and consists of microtubules and micro filaments

Contains contractile proteins and is responsible for cell shape changes

Question 6

Organelle zone (granulomere)

Answer 6

Rest of the platelet, includes all the cytoplasm and its component

Cytoplasm: granules and canal systems

Question 7

Granules store the many important substances found in platelets including

Answer 7

Vasoconstrictor substances

PF3 (platelet factor 3)

Antiplasmin and anti-heparin

Substances that promote platelet aggregation

Calcium

Question 8

The canal systems function

Answer 8

Carry the contents of the granules from the interior of the cell to the exterior during the “release reaction”

Question 9

Platelet distribution

Answer 9

Only 70% of the platelets are circulating
30% sequestered- 17% in the splenic sinusoids and 13% in the Microcirculation and sinusoids of the liver, lungs and bone marrow